'Up in arms' started as a literal expression in the sixteenth century which became a more figurative idiomatic expression during the seventeenth century. This old cliche is still quite familiar today.

Meaning of being 'Up in Arms'

To be up in arms means to be angrily protesting something in a quite public manner, or to be openly rebellious. When someone is up in arms, they are not only angry, but they are letting everyone know about it.

We no longer have to take up arms to be up in arms over something

We no longer have to /take up arms// to be up in arms over something

Usage

The expression 'up in arms' is usually followed by a phrase starting with over or about such as "The employees were up in arms over not being paid overtime wages."

Examples:

"Democrats are up in arms about the new health care bill."

"Protestors, up in arms over the administration's climate policies, gathered in front of the White House."

Origin

When this expression first came to use, it meant to literally take up arms against a perceived enemy. For example, it appeared in Jonathan Swifts first major work, A Tale of a Tub, published in 1704: "All the men of wit and politeness were immediately up in arms through indignation."

Usage

The expression 'up in arms' is usually followed by a phrase starting with over or about such as "The employees were up in arms over not being paid overtime wages."